UNIX for Dummies Questions & Answers

1,APRIL,NEW,"New market,delhi,pune,India",RECENT, 254664
2,MARCH,OLD,"New Area,Mumbai,UP,India",CURRENT, 152483

1,APRIL,RECENT,254664
2,MARCH,CURRENT,152483

awk -F, '{ print $1,$2,$(NF-1),$NF}' OFS=, file

echo "a,b,c,d,e,f,g,h" | IFS="," read var1 var2 var3 var4
echo var1=$var1
echo var2=$var2
echo var3=$var3
echo var4=$var4

while IFS="," read f1 f2 junk junk f3 f4 ; do
     echo "$f1,$f2,$f3,$f4"
done < /path/to/input/file

echo "a,b,c,d,e,f,g,h" | {
IFS="," read var1 var2 var3 var4
echo var1=$var1
echo var2=$var2
echo var3=$var3
echo var4=$var4
}

IFS="," read var1 var2 var3 var4 << "_EOT"
a,b,c,d,e,f,g,h
_EOT
echo var1=$var1
echo var2=$var2
echo var3=$var3
echo var4=$var4

#!/usr/bin/env bash

# @(#) s1	Demonstrate separator replacement with perl.

echo
what ~/bin/divepm
# Utility functions: print-as-echo, print-line-with-visual-space, debug.
# export PATH="/usr/local/bin:/usr/bin:/bin"
pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C divepm perl

pl " Modules and versions used by demo perl script p1:"
divepm -q -i=p1

FILE=${1-data1}

pl " Input data file $FILE:"
cat $FILE

pl " Expected output:"
cat expected_output.txt

pl " Results:"
./p1 ',|' $FILE |
tee f1 |
awk 'BEGIN { FS="|"; OFS="|" }{ print $1,$2,$5,$6 }' |
tee f2 |
./p1 '|,'

pl " Demo perl script:"
cat p1

exit 0

$ ./s1

divepm	Display version of perl modules.

Environment: LC_ALL = , LANG = en_US.UTF-8
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian 5.0.8 (lenny, workstation) 
bash GNU bash 3.2.39
divepm (local) 1.4
perl 5.10.0

-----
 Modules and versions used by demo perl script p1:
 1.06	Text::CSV
 1.08	Carp

-----
 Input data file data1:
1,APRIL,NEW,"New market,delhi,pune,India",RECENT, 254664
2,MARCH,OLD,"New Area,Mumbai,UP,India",CURRENT, 152483

-----
 Expected output:
1,APRIL,RECENT,254664
2,MARCH,CURRENT,152483

-----
 Results:
1,APRIL,RECENT,254664
2,MARCH,CURRENT,152483

-----
 Demo perl script:
#!/usr/bin/env perl

# @(#) p1	Demonstrate reconfigure separator for CSV file.
# $Id: p1,v 1.2 2014/03/13 21:47:41 drl Exp drl $

# No checking for errors in this demo version.
# Input separators from command-line,
# Initialize the CSV input and output objects,
# Loop until EOF:
# Read line,
# Parse line with first separator,
# Combine fields into line,
# Print line with new separator.

use Text::CSV;
use Carp;

$comma = ",";
$bell  = "";
$bell  = "|";

$t1   = shift;
$inps = substr( $t1, 0, 1 );
$outs = substr( $t1, 1, 1 );

$csv = Text::CSV->new( { sep_char => $inps, allow_whitespace => 1 } );
$out = Text::CSV->new( { sep_char => $outs } );

while (<>) {
  chomp;
  $line   = $_;
  $status = $csv->parse($line);
  if ( not $status ) {
    carp("problem with csv-parse at $.");
    print "Line $. -- $line";
  }
  @columns = $csv->fields();

  $status = $out->combine(@columns);
  if ( not $status ) {
    carp("problem with csv-combine at $.");
    print "Line $. -- $line";
  }
  $line = $out->string();
  print "$line\n";
}

sed 's/"[^"]*"//'g /path/to/input |\
while IFS="," read f1 f2 junk junk f3 f4 ; do
     echo "$f1,$f2,$f3,$f4"
done

 
awk -F, '{ print $1,$2,$(NF-1),$NF}' OFS=, file

 
1,APRIL,NEW,"New market,delhi,pune,India",RECENT, 2546642
2,MARCH,OLD,"New Area,street cafe,Mumbai,UP,India",CURRENT, 152483